In a manufacturing process of a semiconductor apparatus, a pattern on a wafer is observed using an apparatus adopting, e.g., a Scanning Electron Microscope (which will be appropriately referred to as “SEM” hereinafter) system, a defect is detected, or a pattern dimension is measured. However, in most conventional SEMs, since secondary electrons from a pattern are mainly detected to form an image, there is almost no secondary electron discharged from the pattern beyond a top face of a pattern as an observation target when an aspect ratio of the pattern is as high as, e.g., above 10, and hence detecting a signal itself is difficult. Therefore, a defect that is present in a pattern having a high aspect ratio cannot be detected, and observation and metrology are also impossible.